1. Field of the Invention
The subject invention relates to electric motors, actuators and actuating methods and, more specifically, to methods of operating or utilizing electric motors, and to apparatus including electric motors, as well as to their design and operation.
2. Disclosure Statement
This disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness, and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments subsequent in time or priority.
In recent years, mechanical actuators have reached a high state of perfection. By way of example, reference may in this respect be had to U.S. Pat. No. 4,174,575, by Kyohiro Nakata, issued Nov. 20, 1979, for Measuring Instrument, and now assigned to the assignee of the subject patent application or patent. One of the measuring instruments disclosed in that patent is a differential micrometer having an adjustment precision of one-half micrometer or 0.0005 millimeters. While that micrometer is, of course, very useful as a measuring instrument, it also serves as a high-precision actuator in such delicate applications an optical component adjustment in holographic or other laser beam utilization systems. A disadvantage of using differential micrometers as component actuators is, however, that they are manually operated.
Attempts have thus been made to provide electrically energized actuators which could take the place of the manually operated micrometer type. Accordingly, a small electric motor with reduction gearhead has been accommodated in a tubular housing, for axial movement. The output shaft of the gearhead was attached to a threaded spindle which extended through an internal thread in a front piece of the housing. To inhibit rotation of the motor and gearhead, a longitudinal keyway was provided in the housing, while an antirotation device having a key projection running in the keyway was attached to the gearhead. The motor through its gearhead rotated the threaded spindle, which thus at least in theory would translatorily move out of and alternatively into the internally threaded front piece of the housing.
In practice, the latter approach has several problems. For one thing, the key device would pivot or cant when running under load, thereby incurring side loads from torquing. On the other hand, attempts at reducing the side load exposed the gearhead to disintegration when the spindle was reaching its extremity of translatory motion.